Review of the asthma mortality rate for Minnesota residents aged 55 years or older, 2004-2005: when death certificates deserve a second look

Asthma mortality rates are based on deaths for which asthma is coded as the underlying cause on the death certificate. We conducted an asthma mortality review to evaluate this surveillance measure for Minnesota residents who were aged 55 years or older We enlisted an expert panel to review transcribed interviews from the next-of-kin and case histories for decedents whose deaths were attributed to asthma. In addition, we examined death certificates to determine whether the certifier had intended asthma to be the underlying cause. In the age group of Minnesotans we examined, 55 deaths were attributed to asthma during the 1-year study period. Of the 35 deaths for which adequate information was available for review, 2 were determined to be due to asthma. On 33 of the 55 death certificates, the certifier had chosen asthma as the underlying cause; on the rest, the certifier had not chosen asthma, but inconsistencies in death certificate completion had resulted in "asthma" automatically overriding the underlying cause that had been chosen. Asthma mortality rates for older Minnesotans may be overestimated because of inaccurate reporting of the underlying cause of death on death certificates.